JP2004073875A - Blood flow circulation assist device using continuous flow blood pump and blood flow circulation state diagnostic device for living body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a blood circulation assisting device capable of detecting a blood circulation state in a living body without requiring a special sensor and capable of performing a good circulation assist suitable for the blood circulation state of the living body.
SOLUTION: A continuous flow blood pump 1, a blood removal vessel 2 and a blood supply vessel 3 are provided, and blood is ejected by the pump. A flow rate detecting means 7 for obtaining information on a flow rate flowing through the pump; a flow rate amplitude detecting means 8 for outputting a flow rate amplitude which is a difference between a maximum value and a minimum value of an output of the flow rate detecting means at a predetermined time interval; The number of rotations of the motor is changed over a predetermined range, and based on the change in the flow rate amplitude, the point t at which the circulating assistance by the pump shifts from partial assistance to complete assistance, or the blood inlet of the devascularization is At least one of the points s, which is a point at which the fluctuation of the flow rate amplitude starts to be noticeable after starting to stick to the living body wall, is detected, so that the detected t point or the s point corresponds to a predetermined relationship with the rotation speed of the motor. And control means 5 for controlling the motor.
[Selection diagram] Fig. 1

Description

The present invention relates to a blood circulation assisting device using a continuous-flow blood pump for assisting blood supply, and a diagnostic device for a blood circulation state of a living body using the blood circulation assisting device.

拍 As a pulsatile blood pump used for assisting blood circulation, there are positive displacement pumps such as a diaphragm type pump and a pusher plate type pump. In a positive displacement pump, pump drive control that meets the needs of the living body is performed by driving the pump in a full fill-complete pump mode. However, it is extremely difficult to develop a positive displacement pump as an artificial heart due to its complicated mechanism.

On the other hand, for a continuous flow blood pump, in addition to typical pumps such as a centrifugal pump, an axial pump, and a mixed flow pump, a rotating body, a precession body, an oscillating body, or vibration or wave motion is used. Pumps that expel blood by pressure have been developed for the purpose of assisting the circulation of living bodies. These are more promising than positive displacement pumps because their mechanisms are simple and inexpensive to manufacture. However, continuous flow blood pumps are more difficult to control than positive displacement pumps.

In order to provide circulatory support that meets the needs of the living body, a method of monitoring blood pressure, blood flow of pumps and living bodies, sympathetic nervous activity, venous oxygen saturation, etc., alone or in combination, using special sensors has been devised. Have been. However, the development of a sensor that can be used continuously without replacement for a long time has not been advanced.

Also, as a method of controlling the driving of the continuous flow blood pump without using a special sensor, the ejection flow rate of the pump is estimated from the average value of the current consumed by the motor and the driving characteristics of the pump used, and the flow rate is estimated. A method of performing control so as to be constant has been proposed. That is, in the continuous flow blood pump, it is possible to obtain the mutual relationship among the rotation speed of the pump, the generated head (pressure), the ejection flow rate, and the motor current consumption. Therefore, if the rotation speed and the motor current consumption are known, the generated head and the ejection flow rate of the pump at that time can be estimated. In addition, since the rotation speed and the current consumption of the motor can be extracted and used as internal data of the motor without using a special sensor, the rotation speed can be controlled with a simple configuration so that the flow rate is constant. (See Non-Patent Document 1).
"Control of Centrifugal Blood Pumo Based on the Motor Current", Tatsuhiko Iijima, et.al., Artificial Organs Vol. 21, No. 7, 1997, Japanese Society of Artificial Organs

However, there are some problems in the method of estimating the ejection flow rate of the pump from the average value of the motor current consumption and the drive characteristics of the pump used, and performing control so that the flow rate is kept constant.

(1) The first problem is that it is impossible to perform appropriate circulatory assistance of blood of a living body with the control method. The blood flow required by a living body greatly varies depending on the individual situation of the living body. For example, individual size, activity status, circulating blood volume, etc. of an individual affect the optimal blood flow. Specifically, for a 10 kg infant, the normal cardiac output is about 1 L / min, and during exercise of an adult, the cardiac output may exceed 10 L / min. Therefore, a control method that simply keeps the ejection flow rate of the pump constant is inappropriate when performing appropriate circulation assist of the blood of the living body.

The second problem is that the consumption current of the motor is affected by the kinematic viscosity of the liquid during liquid sending.For example, when the liquid is blood, if its properties change, it is difficult to estimate the ejection flow rate. The point is that a large error occurs. Factors affecting the kinematic viscosity of blood include the number of red blood cells (or hematocrit), serum lipid levels, and serum total protein levels. These values vary depending on the physiological state of the living body. However, no method has been devised for continuously monitoring the kinematic viscosity of blood or the concentration of blood components. Therefore, it is difficult to realize a method of controlling the liquid supply so as to obtain a desired flow rate without being affected by the properties of blood, for example, kinematic viscosity.

In order to solve the problems of the prior art as described above, the present invention detects the blood circulation state of a living body without requiring a special sensor for monitoring the properties of blood, and responds to the blood circulation state of the living body. It is another object of the present invention to provide a blood circulation assisting device using a continuous flow blood pump that can perform appropriate circulation assistance.

The blood circulation assisting device according to the present invention includes a continuous flow blood pump constituted by a non-volume pump for assisting blood flow, and a continuous blood pump having one end attachable to a blood removal site of a living body and the other end connected to the continuous blood flow. A blood removal vessel connected to the inflow part of the pump, and a blood supply vessel whose one end is attachable to the blood sending part of the living body and the other end is connected to the outflow part of the continuous flow blood pump, and blood is removed through the blood removal vessel And a device for ejecting blood to a predetermined flow rate through the blood supply vessel by the continuous flow blood pump.

In order to solve the above-mentioned problems, a flow rate detecting means for directly or indirectly obtaining information corresponding to a flow rate of blood flowing through the continuous flow blood pump, and an output of the flow rate detecting means, the flow rate at a predetermined time interval, A flow amplitude detector that detects a maximum value and a minimum value of the output of the detector and outputs a flow amplitude that is a difference between the maximum value and the minimum value, and a rotation speed of a motor that drives the continuous flow blood pump is set within a predetermined range. At the point t, at which the circulating assistance by the pump shifts from partial assistance to complete assistance, based on the change in the output of the flow amplitude detection means, or the blood inlet of the devascularization is By detecting at least one of the s points, which is a point at which the fluctuation of the flow rate amplitude starts to become remarkable by starting to stick to the living body wall, at least one of the detected t point or s point So as to have a predetermined relationship with respect to the rotational speed of the motor to respond, and control means for controlling the rotational speed of the motor.

According to the device having the above configuration, the point t or the point s corresponding to the blood circulation state in the living body is detected based on the flow amplitude value at the predetermined time interval, and the operation of the pump is controlled based on the detected point t or s. In addition, good circulatory assistance suitable for the blood circulation state of the living body can be easily performed.

In order to further clarify that the object of the present invention can be achieved by using the blood circulation assist device of the present invention, the clinical background related to blood circulation assist and the more detailed operation of the device having the above configuration will be described below. explain.

<Pulsation of current consumption waveform of continuous flow blood pump>
In a continuous flow pump, under normal operating conditions, the flow ejected from the pump is a steady flow, and the current consumption does not show any pulsation. On the other hand, the heart of a living body shows a pulsatile flow unless it is stopped or in an arrhythmic state comparable to the stop. Therefore, when a continuous flow pump is used for a living body to assist circulation, a flow that is pumped out by a pump that should be a steady flow is affected by the heart of the living body and shows pulsation. As a result, the current consumption waveform of the motor driving the pump shows pulsation.

The present inventor pays attention to the pulsation that specifically appears when used in a living body, and can perform appropriate circulation assistance based on the pulsation of the current consumption value, not the average value of the current consumption of the motor. Thus, the present invention was configured.

<Relationship between motor speed and current consumption waveform>
In the following description, "complete support" with respect to blood flow circulatory support refers to a case where no blood is ejected from the heart of a living body and all blood is ejected from a blood pump. However, this does not mean that the heart of the living body is stopped. Therefore, the heart of the living body may generate some pressure. On the other hand, "partial assistance" refers to a state in which the heart of the living body is pumping blood and the blood pump is simultaneously ejecting blood.

1) Point t At low rotation, the driving force of the heart of the living body exceeds the driving force of the pump, and the circulation of the living body becomes a pulsating flow. As a result, the pulsation is also observed in the current consumption waveform of the motor. As the rotation is increased, the drive power of the pump becomes closer to the blood drive power of the living heart, and eventually becomes equivalent. This point is referred to as a point t (derived from a total assist point) in the present invention. When the rotation speed is further increased after the point t, the drive force of the pump surpasses the drive force of the living body heart, so that blood is no longer emitted from the living body heart, and the circulatory support shifts from partial support to complete support. I do. Therefore, the circulation of the living body changes from a pulsating flow to a steady flow. As a result, the pulsation appearing in the current consumption waveform of the motor decreases.

様 子 This situation is shown in the graph of FIG. The graph shows an example of the relationship between the number of rotations of the motor and each monitor index. Since this graph will be described in detail later, only the current amplitude index will be focused on here. The current amplitude index is a value obtained by dividing the amplitude of the current fluctuation by the current average value at that time. The reason for using the current amplitude index is as follows.

る た め Since the average value of the motor current consumption increases with the number of rotations, the magnitude of the current consumption amplitude also tends to increase with the increase of the number of rotations, even if the state of the living body does not change. Therefore, it is difficult to directly detect the change in the pulsatile flow in the circulation of the living body from the change in the amplitude of the current fluctuation. That is, the absolute value of the amplitude of the current fluctuation includes the influence of the change in the motor speed. Therefore, in order to extract only the change in the pulsating flow in the circulation of the living body, it is desirable to use the current amplitude index as an index. As will be described later, such indexing is essentially unnecessary when a change in pulsatile flow is detected using a flow meter that directly measures the blood flow rate instead of the motor current consumption.

The tp point and the ti point are points corresponding to the above-mentioned t point. However, in order to distinguish the point where the circulatory assist of the pump shifts from partial to complete according to the identification method, the contraction is performed. A point identified from the arterial pressure and the systolic left ventricular pressure is defined as a point tp, and a point identified from the current amplitude index is defined as a point ti. As will be described later, the two points substantially match. The point t in the description of this section is the point ti.

と お り As is clear from FIG. 1, the point t is a peculiar point that appears very clearly as the motor speed increases.

2) About point s As the rotation speed of the pump increases, the phenomenon of sticking to the blood removal site starts to occur. Since suction usually occurs intermittently in accordance with the heartbeat of a living body, the suction causes the blood flow of the pump to pulsate. In the state where the blood removal of the pump is appropriate and the circulating blood volume is not insufficient, the suction is higher than the state where the circulation between the living body and the pump is very close to the steady flow at a higher rotation than the point t. It becomes noticeable with rotation. Therefore, the magnitude of the fluctuation amplitude in the consumed current waveform becomes minimum when approaching a steady flow, and increases again when sticking becomes remarkable. This point is referred to as an s point (derived from a sucking point) in the present invention. As shown in FIG. 1, beyond the point s, the current amplitude index starts to increase.

As described above, the relationship between the rotation speed of the motor and the amplitude of the current fluctuation is represented by the rotation speed of the motor and the current amplitude index (the value obtained by dividing the amplitude by the current average value). There are two unusual points, a point t that shifts to and a point s where the blood flow pulsation of the pump due to sucking starts.

<Meaning of singular points t and s, its application to diagnosis of circulatory state of living body and pump control>
Point t is the point at which the circulation assist of the pump shifts from partial assistance to complete assistance as described above. In order to be able to provide this full support, the pump must drive all of the venous return and must be able to generate a head that allows the pump to maintain flow. The head is the pressure difference between the suction pipe and the discharge pipe of the pump, and greatly depends on the blood pressure on the blood sending side in a living body. Since this blood pressure is defined by the amount of venous return and the peripheral vascular resistance of the living body, the point t mainly depends on the venous return and the peripheral vascular resistance.

Here, it is assumed that the circulation state of the living body changes and the rotation speed corresponding to the point t changes. In this case, an increase in the number of revolutions means that if the blood pressure does not change, the venous return increases, and if the venous return does not change, it means that the blood pressure increases. The decrease in the number of rotations is because a phenomenon opposite to the above phenomenon has occurred. That is, since the change in the point t corresponds to the change in the circulatory state of the living body, the rotation speed of the pump is controlled, for example, so as to be always at the point t or near the point t. In addition, circulatory support that is sufficient for the living body can be realized.

Note that the vicinity of the point t means a range in which sufficient accuracy for practical use can be obtained for estimating a change in the circulatory state of the living body. For example, the rotation in the range of ± 2 to 3% with respect to the rotation speed at the point t. Number.

However, performing control on the basis of the point t is an example showing that it is possible to perform control according to the circulatory state of a living body using the amplitude of the flow rate variation, here the amplitude of the current consumption variation of the motor, The control criteria can be selected according to the purpose.

Although only the circulatory assistance has been described in the above description, the inflow state of the blood inlet and the heart filling state can be diagnosed by using the magnitude of the fluctuation in the current consumption waveform at or near the point t. It is possible.

The s point is the point at which the pulsation of the pump blood flow due to the suction starts to become remarkable. If there is no problem in the blood inflow part of the devascularization of the pump and suction is unlikely to occur, the magnitude of the current value fluctuation at or near the s point reflects the steady flow of the pump. Almost zero. Therefore, by knowing the magnitude of the current amplitude at the point s, the problem of the blood inflow portion of the devascularization of the pump, specifically, poor blood removal due to the deviation of the devascularization, occurrence of thrombus and other obstacles, Alternatively, since a problem such as a remarkable decrease in circulating blood volume (dehydration or shock) can be found, it is possible to appropriately control blood circulation assistance. Even if the control is not exactly at the s point, the control can be performed to a practically satisfactory level by knowing the magnitude of the amplitude of the current value fluctuation near the s point. The vicinity of the s point means a range in which sufficient accuracy for practical use is obtained for estimating a change in the circulatory state of the living body. For example, the rotation speed in a range of ± 2 to 3% with respect to the rotation speed of the s point. I do. The “almost 0” refers to the magnitude of the current amplitude in a range where the problem can be found at or near the s point and the blood circulation assist can be appropriately controlled.

点 The point s or the vicinity of the point s is a point where no remarkable sticking occurs and the pressure generated by the heart of the living body is minimized. This means that the effect of reducing the burden on the heart can be obtained safely and maximally. Therefore, by controlling the rotation speed of the pump so as to be always at or near the s point, a safe and maximum burden reducing effect for the heart can be realized.

As is apparent from the above description, by controlling the rotation speed of the pump to be always between the vicinity of the point t and the vicinity of the s point, there is no excess or deficiency for the living body, and the effect of reducing the burden on the heart is maximized. Safe and effective circulation assistance can be realized.

<Control index>
All indices based on the measured parameters reflected in the continuous flow blood pump under the influence of the pulsation of the living body can be used for controlling the pump device. In the present invention, the magnitude of the pulsation amplitude is used as such a control index. If the current value of the pump motor is used, a numerical value that is indexed based on the magnitude of the amplitude of the pulsation of the current value may be used. Specifically, the magnitude of the amplitude of the current value fluctuation of the pump motor divided by the current average value, and the magnitude of the amplitude is the difference between the current consumption during the opening operation and the closing operation of the pump at the same rotation speed. (Theoretical maximum amplitude). Here, "at the time of the opening operation" refers to a case where the operation is performed by opening the conduit connected to the outlet of the pump, and "at the time of the closing operation" is performed by closing the conduit connected to the outlet of the pump. Refers to the case.

<sensor>
In the present invention, a special sensor such as a sensor for monitoring the properties of blood is not required. The detection of blood circulation may be performed by simply measuring the flow rate. The flow rate may be measured directly by using a flow rate sensor or other indirect measuring means.

と し て As the indirect measuring means, for example, the current consumption of the motor of the continuous flow blood pump is used. Since the consumed current becomes electric power by integrating the voltage, electric power may be used. Since the current consumption can be extracted as internal data of the motor, there is no need to use a sensor, in which case the equipment is simplified, reliability and safety are improved, long-term durability is improved, costs are reduced, and downsizing is achieved. And so on.

In addition, a flow sensor such as an ultrasonic flow meter is used as a direct flow measuring means. Even in such a case, since the sensor is used in a conventional manner, the configuration of the device is much easier than when a special sensor for monitoring the properties of blood is required.

<Type of pump, installation place of the pump and period of assistance by the pump>
The pump used in the present invention may be a continuous flow blood pump, and is not limited to a specific pump. Further, the pump may be either an externally installed type or an internally installed type, and the auxiliary period may be short or long. The blood removal site and the blood feeding site of the pump are not limited. There is no limitation of right heart support or left heart support.

As is clear from the above description, the present invention can take various aspects suitable for practical use as described below, in addition to the basic configuration described above.

The flow rate detecting means can be constituted by a flow rate sensor arranged near the continuous flow blood pump. As a result, there is no need for a special sensor for monitoring the properties of blood, and a device that can provide appropriate circulatory assistance according to the clinical blood circulation state of a living body while having a simple structure. realizable.

As an example of the control, the motor may be controlled so that the number of rotations corresponds to the point t or the vicinity of the point t. Alternatively, the motor may be controlled so that the number of rotations corresponds to between the vicinity of the point t and the vicinity of the point s. Alternatively, the motor may be controlled such that the magnitude of the flow amplitude at the point s is substantially zero.

Alternatively, the flow rate detection means for directly or indirectly obtaining information corresponding to the flow rate of blood flowing through the continuous flow blood pump, and the maximum output of the flow rate detection means at a predetermined time interval from the output of the flow rate detection means. A flow amplitude detector that detects a value and a minimum value, and outputs a flow amplitude that is a difference between the maximum value and the minimum value, and changes the rotation speed of a motor that drives the continuous flow blood pump over a predetermined range, Control means for controlling the number of rotations of the motor to a range where the relationship between the number of rotations of the motor and the magnitude of the flow rate amplitude has a negative correlation based on a change in the output of the flow rate amplitude detection means. It can also be set as the structure.

With these configurations, it is possible to realize a device that is safe for the heart and has a maximum burden reducing effect.

The blood flow assisting device having the above-described configuration is provided, and based on the detected magnitude of the flow amplitude at or near the point t or at or near the point s, the inflow state of the blood inlet and / or the filling of the heart. The diagnostic device for the blood circulation state can be configured to detect the condition.

Alternatively, the blood flow assisting device having the above configuration is provided, and the change in the motor rotation speed corresponding to the detected point t or its vicinity, or the point s or its vicinity is detected. By detecting a change in the circulation state, a diagnostic apparatus for the blood circulation state can be configured.

In the diagnostic device, when the rotation speed of the motor corresponding to the point t or the vicinity of the point t increases, if the blood pressure is unchanged, it is determined that the venous return has increased, and the venous return has not changed. In such a case, it can be configured to determine that the blood pressure has increased. Alternatively, when the rotation speed of the motor corresponding to the point t or near the point t decreases, it is determined that the venous return has decreased if the blood pressure has not changed, and if the venous return has not changed, the blood pressure has not changed. May be determined to have decreased.

According to the blood circulation state diagnostic apparatus described above, a simple configuration can be used to easily diagnose the blood circulation state of a living body, or to prevent the occurrence of injuries caused by sticking. A diagnostic device for performing this can be realized.

Hereinafter, the blood circulation assisting device according to the embodiment of the present invention will be specifically described with reference to the drawings.

FIG. 2A is a block diagram showing a blood circulation assisting device according to an embodiment of the present invention. Reference numeral 1 denotes a continuous-flow blood pump, which ejects blood using a centrifugal pump, an axial-flow pump, a mixed-flow pump, or a rotating body, a precession body, a swinging body, vibration, or a wave. Various pumps, such as a pump, can be used. The suction port of the pump 1 is connected to a blood removal vessel 2, and the discharge port thereof is connected to a blood supply vessel 3. In using the device, the free end of the blood removal vessel 2 is attached to the blood removal site of the living body, and the free end of the blood supply vessel 3 is attached to the blood transmission site. The pump 1 is driven by a motor 4.

The motor 4 is connected to the power supply 6 via the control unit 5. The current measuring unit 7 is connected to measure a current consumption flowing through the motor 4. The output of the current measuring unit 7 is applied to the amplitude detecting unit 8. The amplitude detection unit 8 detects the amplitude of the current value fluctuation from the output of the current measurement unit 7 and outputs the amplitude to the control unit 5. The control unit 5 controls the rotation speed of the motor 4 based on the output of the amplitude detection unit 8.

The current measuring unit 7 samples the current waveform at, for example, 120 Hz for 3 seconds, and outputs A / D converted data. In order to detect the magnitude of the amplitude of the output fluctuation, the amplitude detector 8 calculates the maximum value and the minimum value using the data, and obtains the difference between them to obtain the amplitude of the current fluctuation. Can be

Here, the value of the current flowing through the motor 4 detected by the current measuring unit 7 corresponds to the ejection flow rate of the pump 1. Therefore, the magnitude of the current amplitude index output from the amplitude detector 8 ultimately corresponds to the magnitude of the flow amplitude. That is, it will be apparent that the current measuring section 7 constitutes a flow rate detecting means and the amplitude detecting section 8 constitutes a flow rate amplitude detecting means.

However, for the reason described in the section “<Relationship between motor rotation speed and current consumption waveform>” in the disclosure of the invention, the amplitude detection unit 8 is not the current amplitude value itself, but the current fluctuation amplitude value. It is desirable to obtain a current amplitude index, which is a value obtained by dividing the amplitude by the current average value at that time, and output the value.

The current measurement unit 7 needs to be set to have a time for the measurement so that it can detect at least the amplitude of the flow rate fluctuation caused by the interval of the heart beat of the living body.

The control by the control unit 5 is performed, for example, as follows.

(4) The number of rotations of the motor 4 is changed, and the t point or the s point is identified using the current amplitude index output from the amplitude detection unit 8. The motor may be controlled based on the rotation speed corresponding to the identified t point or s point. For example, control is performed so as to maintain the rotation speed near point t.

The identification of the t point or the s point is performed based on the characteristics shown in the graph shown in FIG. As shown in the figure, the current amplitude index stably falls to the right between points t and s. That is, the relationship between the motor speed and the current amplitude index has a negative correlation. Therefore, at fixed time intervals, the rotation speed of the motor 4 is forcibly changed over a sufficient rotation speed range, and if the correlation is detected to be positive or negative, the rotation speed of the motor 4 becomes t point and s. Whether it is in the rotation speed range corresponding to between the points or not can be easily detected. Here, the sufficient rotation speed range means that it is enough to exclude a temporary increase and decrease in the current amplitude index, which appears at a rotation speed higher than the point s shown in FIG. Just fine. In this way, the start of the rotation speed range where the relationship between the motor rotation speed and the current amplitude index has a negative correlation is detected, and the start point is identified as point t. Similarly, for the s point, the end of the same rotational speed range may be detected, and that point may be identified as the s point. Such processing can be easily realized by a computer if the output of the amplitude detector 8 is digitized as described above.

制 御 Control utilizing the above finding, that is, the fact that the relationship between the motor speed and the current amplitude index has a negative correlation when the motor speed is between the point t and the point s is also effective. That is, the rotation speed of the motor 4 is forcibly changed for a certain period of time, the state of the correlation is detected, and the rotation speed of the motor 4 is controlled in a range where the correlation is negative. If a negative correlation is not obtained by one operation, the motor 4 is driven again in a different rotation speed range. With such control, the motor can be easily controlled so that the rotational speed is between the points t and s without actually detecting the points t and s. The rotation speed may be changed by increasing or decreasing the rotation speed of the motor 4 within a predetermined range.

The timing of the detection of the point t or the point s, or the detection of whether or not the number of rotations of the motor is in a desired range as described above, may be appropriately determined according to the clinical situation.

In the above-described embodiment, the current measuring unit 7 is used as a means for measuring the ejection flow rate by the pump 1, and a value corresponding to the flow rate is obtained from the current value. However, the flow rate is directly measured using the flow rate sensor. You may. For example, a configuration in which an ultrasonic flowmeter is attached to the blood supply vessel 3 and the output of the ultrasonic flowmeter is processed by the amplitude detector 8 is also possible. In this case, the amplitude detector 8 serving as the flow amplitude detector may output the magnitude of the output fluctuation itself of the flow sensor, and need not be indexed as in the case where the current value of the motor 4 is used. Absent.

If the input signal from the current measuring unit 7 is digitally processed as described above, the analysis, diagnosis, and control can be easily automated by a computer program. However, even in the case of an analog signal, the current amplitude can be visually displayed, and the analysis, diagnosis, and control can be performed manually, which is also a simple and effective method. Of course, a similar apparatus including manual operation may be configured using digitally processed signals. An example of such a device is shown in FIG.

In FIG. 2B, the configurations of a pump 1, a blood removal vessel 2, a blood vessel 3, a motor 4, a current measuring unit 7, and an amplitude detecting unit 8 are the same as those in the above-described embodiment, and therefore description thereof is omitted. I do. The motor 4 is connected to a power source 6 via an adjusting unit 9. The output of the amplitude detector 8 is applied to the display 10. That is, information indicating the amplitude of the detected current fluctuation is visually provided by the display unit 10. Based on the information, the operator can operate the adjusting unit 9 to adjust the operation of the motor 4 to an appropriate state.

The information displayed on the display unit 10 can take various forms. For example, a numerical value representing the magnitude of the current amplitude, a maximum value and a minimum value of the amplitude, a current amplitude exponent value, and the like can be used. Alternatively, the waveform may indicate a change in the current amplitude or the current amplitude index.

In the case of using the device of the present embodiment, it is possible to display the change waveform of the current amplitude on the display unit 10 and visually identify the point t or the point s.

When performing diagnosis and control manually, it is effective to provide the device with a function for displaying when the current drive of the pump is near the point ti or near the point s. It is. These analysis, diagnosis, and control systems can be miniaturized and simplified by incorporating them into a motor controller, but they may be separate devices.

装置 The above device can be used for both short-term assistance and long-term assistance. Such a device may be installed outside the body or may be implanted inside the body.

装置 Furthermore, a device for diagnosing the state of blood circulation in a living body can be configured using the device of the above embodiment. For example, if the apparatus shown in FIG. 2B is used, it is possible to determine the circulation state from the contents displayed on the display unit 10. Further, it is more convenient if the output of the amplitude detector 8 is further processed and displayed on the display 10 as an index directly representing the circulation state.

Hereinafter, an experimental example in an animal experiment will be described in which the blood circulation assisting device of the present invention is attached to a living body and used for assisting blood circulation in the living body.

(Experimental example 1)
Eight beagle dogs (body weight 10.2 to 17.2 kg, average 13.6 kg) were used. The heart was exposed by left fifth intercostal thoracotomy under general anesthesia by endotracheal intubation and controlled breathing. Devascularization was performed by inserting the blood inflow site into the left ventricle in a transmitral manner from the left atrial appendage, and the blood supply vessel was end-anastomized to the descending thoracic aorta. As the pump, a mixed flow pump having an impeller diameter of 32 mm was used. The waveforms of the pump current consumption, aortic pressure, left ventricular pressure, and pump flow were monitored. The rotation speed was continuously increased from 2300 rpm to 5000 rpm. FIG. 1 shows an example of the relationship between the rotation speed and each monitor index.

平均 Since the average value of the motor current consumption increases with the rotation speed, the magnitude of the amplitude also tends to increase. Therefore, in order to clarify the change in the magnitude of the amplitude, a value obtained by dividing the magnitude of the amplitude by the current average value at that time was used as an index as a current amplitude index.

The points identified from the systolic arterial pressure and the systolic left ventricular pressure were identified from the tp point and the current amplitude index in order to distinguish the point where the circulatory assist of the pump transitions from partial to complete by the identification method. Let the point be the ti point. As is clear from FIG. 1, the current amplitude index peaking at the point ti becomes minimum at the point s. Both the ti point and the s point are unique points, and identification is easy.

When the rotation speed is higher than the s point, the current waveform becomes a disturbed waveform peculiar to sticking, and the current amplitude index increases again. In this graph, the rotation speed at point ti was 2800 rpm, and the rotation speed at point s was 3600 rpm. Focusing on the systolic arterial pressure and the systolic left ventricular pressure, as the rotational speed increases, the systolic arterial pressure and the systolic left ventricular pressure match up to the tp point, but pass the tp point. And the systolic left ventricular pressure decreases. In this state, the aortic valve does not open, and there is no pumping of blood from the left ventricle into the aorta. This means that the pump has shifted from partial assistance to full assistance.

で は In this experiment, the rotational speeds at points tp and ti are completely the same. The point ti identified from the current amplitude index coincides with the point at which the pump transitioned from partial assistance to full assistance. The systolic left ventricular pressure decreases to the point s, but decreases only to the point s and does not decrease at higher rotations. Therefore, the reduction of the load on the heart is the maximum at the point s, and a higher rotation beyond this is dangerous because heart damage due to remarkable sticking occurs. Pump flow increases with increasing rotating bed.

心 拍 In this experiment, the cardiac output before mounting the pump was 0.92 L / min. Since the pump blood flow at the point ti in the graph of FIG. 1 is 1.1 L / min, the flow almost coincides with the venous return at the point ti. From point ti to point s, the pump blood flow is increasing, but considering that the arterial pressure has not increased, it is not an effective increase in blood flow to the living body but a regurgitation at the aortic valve. It is thought to reflect an invalid increase in blood flow. At a rotation higher than the point s, the pump blood flow does not increase because of the remarkable suction.

The t and s points can be identified by actively changing the rotation speed of the pump and automatically determining the relationship between the rotation speed and the current amplitude index by a computer. The operation of changing the rotation speed may be performed all the time, intermittently, or may be performed when any abnormality is detected.

In this experiment, the t point and the s point are identified by measuring the systolic left heart pressure, the current amplitude index, and the like in the range of the change in the rotation speed of the pump in the range of 2000 to 5000 rpm. It is not always necessary to increase the change width of the rotation speed as described above. For example, the change width is performed at about 100 rpm, and if the relationship between the rotation speed and the current amplitude index is negatively correlated, from the point t. It is considered that it is driven between the s points. Therefore, it is preferable to control the rotation speed of the pump between points t and s including points t and s, and between points t and s including points t and s.

(Experimental example 2)
Eight beagle dogs were prepared for heart failure by temporary coronary artery blockade and subjected to an infusion load test. A total of three locations of the central and peripheral branches of the anterior descending coronary artery and the main branch of the circumflex branch (usually a blunt branch) were released after 30 minutes of interruption. After the release, cardiac support was performed by a pump for 120 minutes, and finally, 500 ml of low-molecular-weight dextran was rapidly infused to perform an infusion load. Identification tests at points t and s were performed by temporarily and continuously changing the number of revolutions of the coronary artery for a total of seven times before, during, and after the blockage, 30 minutes, 60 minutes, 90 minutes, and 120 minutes, and after the infusion load. Statistical processing was performed for the measurement of the identification test at t point and s point for a total of 52 times.

Looking at the relationship between the tp point identified from the systolic arterial pressure and the systolic left ventricular pressure and the ti point identified from the current amplitude index, the rotational speeds of both (Nt-p and Nt-i) , A high correlation was recognized (multiple correlation coefficient R ＾ 2 = 0.787), and a significant regression coefficient was obtained (risk rate P <0.0001) (FIG. 2). From this result, it was considered that the diagnosis of the auxiliary state of the pump was possible from the current amplitude.

In order to examine the significance of the pump control at the point t, the left ventricle dp / dt (dp / dt) measured with the pump flow rate (Qt-i) at the point ti as an objective variable and the pump momentarily shut off , Left ventricular end diastolic pressure (LVEDP) and systolic aortic pressure (AoPsys) were used as explanatory variables, and a high correlation was found when multiple regression analysis was performed (multiple correlation coefficient R ＾ 2 = 0.559). . In each regression coefficient test, only LVEDP was significant (dp / dt: P = 0.21, LVEDP: P <0.0001, AoPsys: P = 0.37).

The dp / dt is obtained by differentiating the change in pressure with time, indicates the change in pressure with time, and is a clinical index of cardiac contractility.

Each single correlation coefficient is R ＾ 2 = 0.0013 (FIG. 3) between the pump flow rate at the point ti and the left ventricle dp / dt, and between the pump flow rate and the LVEDP at the point ti. R ＾ 2 = 0.474 (FIG. 4), and R ＾ 2 = 0.144 between the pump flow rate and the systolic aortic pressure (AoPsys) at point ti (FIG. 5).

に よ り Based on these results, the pump flow rate at the point ti has a high correlation with the left ventricular end-diastolic pressure (LVEDP). That is, it is considered that the pump flow rate at the point ti is determined by the preload of the left ventricle (indicating the amount of blood returning to the heart) and does not depend on the contraction force or the afterload of the left ventricle. This is impossible and wasteful in that it pumps out the amount of blood present in the heart, and it can be said that this is close to the control of a natural heart or a pulsatile total artificial heart.

ADVANTAGE OF THE INVENTION According to this invention, the blood circulation state in a living body can be detected without needing a special sensor, whereby it is possible to easily perform good circulatory assistance adapted to the blood circulation state of the living body, Useful for auxiliary equipment.

4 is a graph illustrating an example of a relationship between a rotation speed of a motor driving a pump and each monitor index according to the embodiment of the present invention. (A) is a block diagram showing a blood circulation assisting device according to one embodiment of the present invention, and (b) is a block diagram showing a blood circulation assisting device according to another embodiment of the present invention. The figure which shows the relationship of the rotation speed of tp point and ti point in embodiment of this invention. The figure which shows the relationship between the pump flow rate and the left ventricle dp / dt at the same ti point. The figure which shows the relationship between the pump flow rate and the left ventricular end-diastolic pressure at the point ti. The figure which shows the relationship between the pump flow rate and the systolic aortic pressure at the same ti point.

Explanation of reference numerals

Reference Signs List 1 pump 2 blood removal vessel 3 blood supply vessel 4 motor 5 control unit 6 power supply 7 current measurement unit 8 amplitude detection unit 9 adjustment unit 10 display unit

Claims (10)

A continuous flow blood pump constituted by a non-volume pump for assisting blood flow, and a blood removal vessel having one end attachable to a blood removal site of a living body and the other end connected to an inflow portion of the continuous flow blood pump And a blood supply vessel having one end attachable to a blood supply site of a living body and the other end connected to an outflow portion of the continuous flow blood pump. The blood is removed through the blood removal vessel, and the blood is supplied by the continuous flow blood pump. In a blood circulation assisting device that ejects blood to a predetermined flow rate through a blood vessel,
Flow rate detection means for directly or indirectly obtaining information corresponding to the flow rate of blood flowing through the continuous flow blood pump,
From the output of the flow rate detecting means, a maximum value and a minimum value of the output of the flow rate detecting means at a predetermined time interval are detected, and a flow amplitude detecting means for outputting a flow amplitude which is a difference between the maximum value and the minimum value,
The rotation speed of the motor for driving the continuous flow blood pump is changed over a predetermined range, and the circulating assistance by the pump shifts from partial assistance to complete assistance based on a change in the output of the flow rate amplitude detecting means. At least one of a point t, which is a point, and a point s, which is a point at which the blood flow inlet of the devascularization starts to stick to the living body wall, and the fluctuation of the flow rate amplitude starts to be noticeable, is detected, and the detected t point or control means for controlling the number of revolutions of the motor so as to have a predetermined relationship with the number of revolutions of the motor corresponding to at least one of the s points. 2. The blood flow circulation assisting device according to claim 1, wherein the flow rate detecting means is configured to obtain an output corresponding to the flow rate by using a flow rate sensor disposed near the continuous flow blood pump. 2. The blood circulation assisting device according to claim 1, wherein the motor is controlled such that the number of rotations corresponds to the point t or the vicinity of the point t. 2. The blood flow circulation assisting device according to claim 1, wherein the motor is controlled so that the number of rotations corresponds to between the vicinity of the point t and the vicinity of the point s. The blood circulation assisting device according to claim 1, wherein the motor is controlled such that the magnitude of the flow amplitude at the point s is substantially zero. A continuous flow blood pump constituted by a non-volume pump for assisting blood flow, and a blood removal vessel having one end attachable to a blood removal site of a living body and the other end connected to an inflow portion of the continuous flow blood pump And a blood supply vessel having one end attachable to a blood supply site of a living body and the other end connected to an outflow portion of the continuous flow blood pump. The blood is removed through the blood removal vessel, and the blood is supplied by the continuous flow blood pump. In a blood circulation assisting device that ejects blood to a predetermined flow rate through a blood vessel,
Flow rate detection means for directly or indirectly obtaining information corresponding to the flow rate of blood flowing through the continuous flow blood pump,
From the output of the flow rate detecting means, a maximum value and a minimum value of the output of the flow rate detecting means at a predetermined time interval are detected, and a flow amplitude detecting means for outputting a flow amplitude which is a difference between the maximum value and the minimum value,
The rotation speed of the motor driving the continuous flow blood pump is changed over a predetermined range, and the relationship between the rotation speed of the motor and the magnitude of the flow amplitude is determined based on a change in the output of the flow amplitude detection means. Control means for controlling the number of revolutions of the motor in a range where the negative correlation is obtained. The blood flow assist device according to claim 1, wherein the inflow state of the blood inlet and / or the heart is determined based on the magnitude of the flow amplitude detected at or near the point t or at or near the point s. A blood flow circulating state diagnostic device configured to detect a full state of blood. Provided with the blood circulation assisting device according to claim 1, detecting a change in the motor rotation speed corresponding to the detected point t or its vicinity, or the point s or its vicinity, and detecting a change in the living body by the change in the rotation speed. An apparatus for diagnosing a circulation state of blood, characterized by detecting a change in circulation state. When the rotation speed of the motor corresponding to the point t or near the point t increases, it is determined that the venous return has increased if the blood pressure has not changed, and the blood pressure has increased if the venous return has not changed. The diagnostic device for blood circulation condition according to claim 8, wherein the diagnostic device is configured to determine that the blood flow has been performed. When the rotation speed of the motor corresponding to the point t or near the point t decreases, it is determined that the venous return has decreased if the blood pressure has not changed, and the blood pressure has decreased if the venous return has not changed. The blood flow circulating state diagnostic device according to claim 8, wherein the diagnosis is performed.

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